Coaxial cable coupling



Oct. 28, 1952 A. H. wArrE, JR

COAXIAL CABLE COUPLING 2 SHEETS-SHEET l Filed March 16, 1943 mmm INVENTR ITE R.

'8 9 27 'BYZM/Q( AAM AITOR EY Patented Oct. 28, 1952 UNITED STATES PATENT OFFICE (Granted under the act of March s, 1883, as amended April 30, 1928; 370 O. G. '757),

5 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The present invention relates to improvements in electrical connectors, and more particularly to an improved coupling means adapted for use with flexible coaxialV cable.

The need for a simple and efcient coupling device for coaxial cable has become more pronounced with the increase in the application of high frequency currents to communications and other fields. For example, in mobile radio apparatus mounted in tanks, trucks, and the like. the antenna mast is made flexible so that it will give and bend readily when meeting obstructions such as low branches of trees, etc. In order to withstand frequent' bendings, such antenna masts must be of strong construction, and the parts associated with the antenna masts must also be of strong and secure construction. This is especially true of the plug for connecting, to the antenna mast, a coaxial cable leading to the radio apparatus.

One type of coaxial cable employed for connecting an antenna mast to a radio apparatus comprises a center conducting core of stranded wire surrounded by a thickness of solid, flexible, high insulation material, which in turn is surrounded by a copper braid, the entire structure having an outer cover of vinyl resin insulation material. There have been many types of connectors and plugs designed and made for the purpose of connecting such cable to another plug, line, or similar cable. Heretofore, it has been generally necessary to apply solder to the outer conducting sheath, resulting in a heating and consequent highly undesirable deformation and even melting of the inner dielectric, as well as entailing additional time and trouble in the application of such device. Another property of the earlier connectors which led to the deformation of the inner dielectric was the excess pressure applied thereto in order to properly retain the coaxial cable. Further, there are present, in the earlier connectors, sharp discontinuities in electrical characteristics as well as abrupt corners in the path of Vthe radio frequency currents, both of which cause excessive losses, due to the formation of frequent discharges and breakdown, and excessive heat.

An object of this invention is to provide an easily applicable coupling member for flexible coaxial cable wherein said coupling member presents a minimum of electrical discontinuity and points of breakdown. i

A further object of the present invention is to provide a coupling for splicing exible coaxial cable wherein the inner dielectric of the cable will not be deformed, and a good electrical and mechanical connection will be secured between both the corresponding outer conductors and inner conductors of the spliced cables, as well as between the cable and connector.

Another object of this invention is to provide a coupling device for flexible coaxial cable, which device issturdy, simple and efficient, and which may be properly applied with maximum ease.

Broadly, the invention comprises a pair of telescoping tubular members having confronting surfaces, at least one of said surfaces being tapered, whereby a exible conducting sheath or an insulating cover or both may be securely engaged between the mentioned surfaces andwhereby the aforesaid surfaces may have the perpendicular distance between them changed by relative longitudinal movement of the tubular members.

More speciically, the improved connector consists of a body member or sleeve having a smooth inner face and a frusto-conically shaped end, a clamp ring with a tapered inner surface, and a locking collar preferably having part of its inner wall tapered, and having a recess for receiving the ring and means for engaging the sleeve. The clamp ring is essentially a shoulder on the locking collar, but is made separate in order that it need not rotate against a clamped conductor when the locking collar is screwed home on the body sleeve. Additional members are provided for engaging and spacing the inner conductors of the cable or line and for properly securing the connector to a desired plug or the like. The connector is applied by cutting the various layers of the coaxial line to properly predetermined offset positions, placingthe inner conductorv and dielectric into the sleeve, inserting the conical end of the sleeve between the sheath and inner dielectric, and employing the clamp ring and the collar member. for securing the conducting sheath and outer insulating cover to the inner sleeve member. By positioning an apertured rod on the inner conductor, the combination is in condition for being conveniently. applied to a properly prepared plug or the like.

Thev various features of the invention will be understood more fully from the following detailed description and the illustrative embodiments shown in the accompanying drawings.

Figure 1 is a side view of a flexible coaxialcable of well known type, showing the various layers forming the cable.

Figure 2 is aside view, partially in section, of

an embodiment of the improved connector shown applied to a coaxial cable.

Figure 3 is a side view of an antenna mast base with the coaxial socket shown partially broken away.

Figure 4 vis a side view partially in section of the preferred embodiment of the invention.

Figure 5 is a longitudinal section of a connection between two cable ends.

Referring to the drawings, and more particularly to Figure l, there is illustrated a flexible coaxial cable formed of an inner conducting core of stranded wire 6, a surrounding dielectric 1, an outer sheath 8 of braided conducting material and an insulating pliable cover 9. It is often necessary to join a coaxial cable to a concentric type of socket so that the .inner conductor is in electrical contact with an inner conductor of the socket and the sheath 8 is in contact with an outer portion of said socket.

In Figure 3, a mast base Ill is shown secured to a bracket I I by means of nuts I2 and threaded extension I3, said bracket Il being positioned on'a'tank, ror other vehicle. 'Depending from extension I3 is socket member I4 having concentric therewith a rigid conducting member I5. The lower outer surface of said socket member ifi is threaded for the purpose of engaging a connector Vplug or the like.

The present invention is utilized for electrically and mechanically securing a coaxial cable to a socket similar to that heretofore shown.

Referring to Figure 4, the improved connector consists specifically of an inner body or sleeve member l1, acoupling collar I8, an inner sleevelike conductor connector I9, an insulating separator 20, a clamp ring or annulus 2| and a locking collar` 22. The inner'surface of the sleeve I7 is -of vcircular cross section, being of uniform diameter zfor a substantial part of the length of said sleeve, thence tapering inwardly at an angle of approximately '7l/2 to the axis of the connector. It has been found that this angleresults in a minimum of reflection and consequent losses. This taper extends `to the inwardly projecting shoulder 23 and a bore vsurface thence extends uniformly lto the 'inner end of the sleevel 7. The outer :surface of member Il has the inn-er end thereof tapered to form the frusto-conical portion 24, which has its extremity tapered to very thin material, but `having a rounded terminal edge, the base of the conical portion extending radially outwardly to form an .annular shoulder 25. The sleeve thence continues rearwardly and has formed on its outer surface, in the following order: A threaded portion 26, hex-nut '21., annular projection .28 (aresulting `channel 33 being thus formed between the projection '28 vandhex- .nut.21') and the uniformfextension 29 which has its extremity 3 9 vinwardly 'swaged `Rotata-bly and slidably secured to the sleeve member 'Il is the coupling collar I8 having an inwardly .projecting retaining flange 3G extending into lthe channel 33, a knurled outer surface 34 and an inner threaded portion 35.

The inner conductor connector I9 isa rodshaped member having its rearward end tapered at the same angle before mentioned and having bores 36 and 31 vaxially'formed therein. As one result of the taper the wall of the bore 37 at the rearward end is very thin, and .its extremity is also rounded, as illustrated. The bore 36 has a diametrically positioned sl-ot 38 extending the length of said bore, whereby vthe surrounding walls may .be .resiliently sprung. Slidably engaging connector I9 is the insulating separator 2l) which is secured within the sleeve I1 by means of swaged outer end 39 and internal shoulder 23 formed on said sleeve. The outer surface of separator 2Q is of the same contour as the inner surface of thesleeve I'I between the shoulder 23 and swaged end l39. The separator 20 is provided wth a longitudinal bore having a recess of enlarged diameter at the tapered end thereof and a reduced diameter, so as to form the shoulder 50, at the opposite end. The separator 20 is made of a low-loss dielectric, such as polystyrene or the like.

The locking collar 22 has formed, on the forward portion of its inner face, an internal thread All which is adapted to engage the external thread 2S of sleeve I1. Extending rearwardly of thread il are the vannular internal groove 42, ledge 43, seat shoulder 44 and the tapered and uniform portions 45 and 45 respectively. The vtaper 45 is of the same slope as the taper-of the frustoconical portion 24 of sleeve vI?! and the .inner surface 46 of th-e tubular extension `418 has a diameter equal to the outer diameter of the insulation of the coaxial cable with which the con-- nector is to be employed.

The forward outer portion of the collar 22 is knurled and the remainder of the said outer s-urface may take |any convenient shape, and in the present device follows the general contour of the innei1 surface.

Positioned within collar 22, beyond the threaded portion 4I thereof, is the clamp ring or annulus 2I which is seated on shoulder 44 and has a flaring flange 41 extending into the groove -42 of collai` 22, the'clamp ring thus being retained within the collar when the-coupling parts lare-disengaged. The inner surface49 ofthe clamor-ing 2| is tapered at the same slope as the fr-ustoconical surface at 24 ofthe sleeve I1.

In applying the improved connector to a coaxial cable, the various 'components of the cable are cut to the offset positions substantially as shown in Figure 1. .The connector I9 is heldso that the bore3'1 faces vupwardly and molten solder is poured therein. The core 6 of the coaxial cable is then inserted .into bore 31 and it is thus apparent that a miniuum of heat will rea-chtheinner dielectric '1.

Thereafter the coaxial cable is inserted intothe collar member 22, .and connector I9 is forced'into the bore of separator `20 until the forwardend of said connect-or -abuts the projecting-shoulder l5I). The cable has been so .cut .that the inn-erdielectric 7 will abut the shouldera-t'th-e innerien'dof the enlarged recess of the separator 20 and will snugly fit within the recess vof the separator'. During the aforesaid positioning `of the :coaxial cable, the frusto-conic'al .portion 2-4 of .the A'sleeve -II is inserted between the .inner dielectric .7l and the conducting sheath 8. It should benoted that the tapered portion 24 of the sleeve I7 :is .surround-ed at its wider part only by the outer conducting sheath 8, and at its terminal po-rtionby both the outer `conductor'sheath andthe insulating cover 9 of 'the coaxial cable. Collar member 221s then screwed onto thesleeve I7., shoulder A44 of said collar member forcing the clamp ring l2l toward the Wider en-d of the frusta-conical portion 24, resulting in a secure engagement of the conducting sheath 8 between-the outer 1surface of the conical portion '$24 andthe inner surface -of the clamp vring Y2 L The outer insulating oo v'er 49 of the cable, as Well as the conducting sheath, is firmly engaged between the surfac'eof the narrower end of the tapered portion 24 and the inner sloped face 45 of the collar` 22. The tubular extension 48 prevents excessive bending of the cable in the vicinity of the joined portions. In coupling the connector of Figure 4 to a socket similar to that shown in Figure 3, a pin I5, having a diameter which will permit a snug fit into the bore 35 of conductor connector I9, is secured to the inner conductor of said socket. This may be done by providing the pin I5 with an axial aperture, and, by means of solder, securing said pin to lthe inner conductor of the socket. The connector is then brought into engagement with the socket so that the pin I5 will pass through the opening in the separator 20 and into frictional fit with conductor connector I9. The coupling collar I8 engages the outer threaded portion of the socket and retains the connector properly secured.

As it is often necessary to join or splice the ends of two lengths of flexible coaxial cable, a slight modification as shown in Figure 2 will permit such utilization of the connector. In this embodiment the collar 22 and clamp ring 2I are similar to the collar and ring of the above described connector, whereas the inner sleeve member 54 differs from the sleeve II of Figure 4 only in that the outer surface of the forward portion (corresponding to socket I4 of Fig. 3) has a thread 52 formed therein and is not supplied with a coupling collar I8 nor the corresponding engaging groove 33. A dielectric separator 53 is screw engaged into an enlarged bore formed in the sleeve 54. The separator 53 has `a longitudinal opening therethrough, one end of which is of such size as to snugly engage the outer surface of the inner dielectric 'I of a flexible cable, the other end being so formed as to frictionally engage a connector pin 55 (corresponding to the one I5). Connector pin 55 has an enlarged head at the inner end thereof, which head has no, abrupt change in surface and is provided with an axial bore which is adapted to engage the core 6 of the coaxial cable. The other end of the pin 55 extends substantially to the end of the sleeve member 54. The connector just described is applied to a coaxial cable in a manner similar to that utilized in the earlier described embodiment.

It is apparent that the front end of the aforesaid connector (at the top in Fig. 2) is of the same general structure as the socket (I4 in Fig. 3) of the antenna mast to which the connector (Figure 4) earlier described was attachable and, as such, said connector of Fig. 2 may be coupled to such latter connector of Fig. 4, as shown in Fig. 5.

There have been shown preferred embodiments of the present invention but it is obvious that numerous changes and omission may be made without departing from the spirit thereof.

I claim:

1. A connector for coaxial cable, comprising a sleeve member having the outer surface of one end thereof tapered and being externally threaded inwardly of the tapered part, means positioned at its other end to couple the sleeve to an outer conductor of an inserted coaxial line, a longitudinally bored dielectric spacer within said sleeve, concentric means within the spacer to connect with the inner conductor of an inserted coaxial line, an internally threaded locking collar adapted to receive the tapered end of said sleeve member free therewithin and to engage the thread on said sleeve member, said locking collar having a concentric annular groove formed on its inner surface positioned so as to surround the tapered end o-f the sleeve member, and a clamp ring rotatably fitted within said locking collar and having an extended flange projecting into and loosely disposed in said annular groove, said inner surface of the locking collar at both sides of the groove being of less diameter than the outer diameter of said flange, said clamp ring having an inner surface confronting the tapered surface of the sleeve member and said two surfaces named being arranged and adapted to clamp therebetween the outer conductor of a coaxial cable end inserted in the locking collar at a locking position of the locking collar on said sleeve member.

2. A connector as claimed in claim l, wherein the locking collar has a portion of its inner surface tapered to the Contour of and located over a part of said tapered end of the sleeve member beyond said groove, and is positioned for wedging on an interposed end of cable insulation.

3. A connector of the character described comprising a sleeve member having a taper formed at one end thereof and an adjacent external thread thereon, an internally threaded coupling collar rotatably connected to the other end of the sleeve, a tapped locking collar engaged slidingly and revolubly around the tapered end of the sleeve engageable with the first named threads of the latter and having an internal concentric groove lcngitudinally outwardly of said threads and over the larger diameter tapered part of the sleeve, a clamp ring having an outwardly projecting flange permanently engaged in said groove for limited longitudinal lost motion within the locking collar and adapted to engage and clamp the outer conductor of a co-am'al cable end against the larger tapered part of the sleeve, a longitudinally bored dielectric spacer positioned within the sleeve at the end opposite the tapered part, and a rod-shaped inner conductor slidably fitted within the dielectric spacer and withdrawable therefrom in the direction of said tapered part, said inner conductor having a cavity formed in at least the end adjacent said tapered part of the sleeve adapted to permanently engage with the axial conductor of a coaxial cable end, the other end of said inner conductor being bored to slidably and separably engage around an axial conductor terminal of an opposed coaxial connector.

4. The structure of claim 3, constituting a first connector; and a second connector comprising a sleeve as in claim 3, a locking collar, clamp ring, and dielectric spacer xed in the sleeve as in claim 3, said sleeve of the second connector being extended beyond the said dielectric spacer at the end distant from the tapered part with an internal diameter to receive the corresponding end of the sleeve of the first connector slidably therein and being exteriorly threaded o-n said extension to engage the internal threads of said coupling collar of the iirst connector, an inner conductor slidable in said spacer of the second connector having a recess therein adjacent the taper of said sleeve to receive permanently the end o-f the inner conductor of a coaxial cable line end opposed to one engaged in the first connector, the last named inner conductor of the second connector having its medial and end portion opposite the recessed end shaped as a plug member slidable in the spacer and withdrawable therefrom in the direction of the tapered part of the sleeve of the second connector, said plug member being slidably and snugly insertable in the said bored end of the inner conductor of the rst connector when said rst and second connectors are presented end-to-end with coaxial cable ends coengaged therewith as described.

5. A connector for coaxial cable made up of an axial inner conductor, a dielectric surrounding said conductor, a coaxial conductor and an outer compressible rubber-like insulation surrounding the coaxial conductor, comprising a sleeve member having an internal diameter approximately the same as the inner diameter of the outer conductor of the said cable and having a taper termination at one end for penetrating insertion in an end of said coaxial cable line under the outer conductor of the line and including a body part with threads intermediate the ends of the sleeve, a tapped locking collar surrounding said tapered end and interiorly threaded at its inner end to engage the intermediate threads of said sleeve member, said locking collar having an internal concentric groove arranged to lie about the larger' tapered part of said sleeve, a clamp ring within the collar and about the larger tapered part of the sleeve and having a circumscribing outwardly projecting flange permanently loosely engaged in and longitudinally movable within the groove, said locking collar having an annular seat shoulder of reduced diameter positoned to engage directly against the side of said ring opposite the body of the sleeve when the threads of the locking collar and said sleeve are coengaged, so as to press the ring into clamping relation to an end portion of the outer conductor of a coaxial cable when laid over and around the said larger tapered part, said locking collar hav- 8, ing a tapered internal surface longitudinally beyond said groove over and around the smaller portion of said tapered part of the sleeve so as to compress a coaxial cable outer insulation against said outer conductor when laid over and around said smaller portion of the tapered part longitudinally beyond said ring when the latter is under compression between said seat shoulder and said outer conductor of a cable end, a longitudinally bored dielectric spacer xed concentrically within said sleeve and stopping short of said tapered part, and an axial conductor member slidably engaged in the bore of the spacer withdrawable therefrom in the direction of the tapered part of the sleeve and adapted to permanently receive the end of the inner conductor of a coaxial cable line end inserted in the connector.

AMORY I-I. WAITE, JR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 699,455 Crunk May 6, 1907 1,060,600 Jamieson May 6, 1913 1,862,833 Stover June 14, 1932 2,241,687 Warnke May 13, 1941 FOREIGN PATENTS Number Country Date 321,343 Great Britain Nov. 7, 1929 515,683 Great Britain Deo. l2, 1939 

